The rabbit visual system offers a unique to 1) stimulate visually a specific class of retinal ganglion cells in isolation and 2) identify the central nuclei in which this particular retinal information is processed. On-type direction-selective ganglion cells respond well to extended targets, such as grating, and to extremely slow velocities of movement. These stimulus parameters preclude responses from any other ganglion cell classes. By appropriate choice of movement directions, each of the subgroups of on-type direction-selective cells can be independently activated. The on-type direction-selective cells are linked to visuo-oculomotor behavior, providing error or comparison signals for the optokinetic nystagmus and vestibuloocular reflex controls systems. The visual stimuli which activate these ganglion cells also evoke responses from neuros in the pretectal nuclei, the terminal nuclei of the accessory optic system, the inferior olive, and the vestibulocerebellum. Using the uptake of 14C-2-deoxyglucose as an indicator of neural activity, the brain nuclei or nuclear subdivisions involved in the on-type direction-selective pathway can be identified. Moreover, variations in the pattern of activity for the different movement directions can be used to determine whether a given central nucleus receives input from one or more of the subgroups. Both pigmented and albino rabbits will be used in this study. Like albinos of other species, albino rabbits have anomalous eye movements, particularly the slow phase of optokinetic nystagmus. Comparing the results of pigmented and albino rabbits can reveal whether an altered central projection of on-type direction-selective information underlies this oculomotor anomaly in the albino. In a way not heretofore possible, this study should reveal a basic tenet of visual system organization; namely, that a specific class of visual information is associated with a unique combination of retinal ganglion cell outputs, neural pathways, central nuclei, and visual behaviors. Although details will vary, this general principle may apply to many species, including man.